The "God Helmet" refers to an experimental apparatus originally called the "Koren helmet" after its inventor Stanley Koren. It was developed by Koren and neuroscientist Michael Persinger to study creativity and the effects of subtle stimulation of thetemporal lobes. Reports by participants of a "sensed presence" while wearing the God helmet brought public attention and resulted in several TV documentaries. The device has been used in Persinger's research in the field of neurotheology, the study of the neural correlates of religion and spirituality. The apparatus, placed on the head of an experimental subject, generates very weak fluctuating magnetic fields, that Persinger refers to as "complex." These fields are approximately as strong as those generated by a land line telephone handset or an ordinary hair dryer, but far weaker than that of an ordinaryrefrigerator magnet and approximately a million times weaker than transcranial magnetic stimulation.
Persinger reports that many subjects have reported " mystical experiences and altered states" while wearing the God Helmet. The foundations of his theory have been criticised in the scientific press, anecdotal reports by journalists,academics and documentarists have been mixed and the effects reported by Persinger have not been independentlyreplicated. The only attempt at replication published in the scientific literature reported a failure to reproduce Persinger's effects and the authors proposed that the suggestibility of participants, improper blinding of participants or idiosyncratic methodology could explain Persinger's results. Persinger argues that the replication was technically flawed, but the Swedish researchers have stood by their replication.
The God Helmet was not specifically designed to elicit visions of God, but to test several of Persinger's hypotheses about brain function. The first of these is the Vectorial Hemisphericity Hypothesis, which proposes that the human sense of self has two components, one on each side of the brain, that ordinarily work together but in which the left hemisphere is usually dominant. Persinger argues that the two hemispheres make different contributions to a single sense of self, but under certain conditions can appear as two separate 'selves'. Persinger and Koren designed the God Helmet in an attempt to create conditions in which contributions to the sense of self from both cerebral hemispheres is disrupted.
The second experimental hypothesis was that when communication between the left and right senses of self is disturbed, as they report it is while wearing the God Helmet, the usually-subordinate 'self' in the right hemisphere intrudes into the awareness of the left-hemispheric dominant self, causing what Persinger refers to as "interhemispheric intrusions".
The third hypothesis was that "visitor experiences" could be explained by such "interhemispheric intrusions" caused by a disruption in "vectorial hemisphericity". Persinger theorises that many paranormal experiences, feelings of having lived past lives, felt presences of non-physical beings, ghosts, muses, and other "spiritual beings", are examples of interhemispheric intrusions.
The God Helmet experiments were also intended, though not specifically designed (see above), to validate the idea that religious and mystic experiences are artifacts of temporal lobe function.
Persinger uses a modified snowmobile helmet that incorporates solenoids placed over the temporal lobes. This device produces magnetic fields that Persinger describes as "weak but complex" (1 microTesla). The pattern of fluctuation in these magnetic fields is derived from physiological sources, for example patterns that appear in EEG traces taken from limbic structures. The purpose of exposing magnetic fields patterned after neurophysiological sources, such as the burst-firing profile of the amygdala, is to enhance the probability of activating the structure from which the signal was derived.Only one of the coils on each side of the helmet is active at any one time, and the active coil changes constantly, "rotating" counterclockwise over each temporal lobe.[relevant? ] Persinger's God Helmet sessions consist of two stimulations, applied one after the other. The first of these uses a signal "tailored from a Chirp Signal sequence, applied over right temporal lobe.[relevant? ] In the second phase of the procedure, both temporal lobes are stimulated, with a pattern derived from the amygdala.
The sessions are conducted with the subject seated in an acoustic chamber. The acoustic chamber is also a Faraday cage, shielding out all EMF emissions and radiation except the Earth's magnetic field. Persinger reports that this shielding allows him to use the apparatus to investigate the effects of geomagnetism on the human brain.
Neither the God Helmet, nor technologies derived from it, are examples of transcranial magnetic stimulation (TMS), which uses magnetic fields on the order of one million times stronger than those used in Persinger's lab. Despite this, Persinger reports similar effect sizes with his apparatus.
Most reports from Persinger's lab consist of people sensing "presences"; people often interpreted these to be that of angels, a deceased being known to the subject, or a group of beings of some kind. There have also been reports in which the participant has experienced what they perceive as God. Persinger reports that "at least" 80 percent of his participants experience a presence beside them in the room, whilst about one percent report an experience of "God",[self-published source?] and others report less evocative experiences of "another consciousness or sentient being".